This invention relates to apparatus for forming permanent splices in optical waveguide fiber, more particularly to apparatus for forming such splices under field conditions where access to the distant ends of the fiber to be spliced is difficult.
A variety of mechanical bonding and glass fusion methods for splicing optical waveguide fibers, and apparatus for carrying out such methods, have been developed. One suitable technique involves an arc-fusion procedure wherein an electric arc is struck across adjacent ends of fibers to be spliced, to melt and permanently fuse the adjacent end sections. U.S. Pat. No. 3,960,531 to Kohanzadeh et al. discloses apparatus suitable for practicing this method.
Exact alignment of the cores of the fibers to be fused is important if a low-loss splice is to be obtained. Field splicing apparatus is available wherein alignment of the fiber end faces can be checked by microscope examination of the joint, but this does not insure optimum core alignment for minimum splicing loss in case the fiber core is not centered in the waveguide. In addition, only one alignment plane at a time can be checked.
Variable-position connectors have been designed which are adjustable to maximize light transmission through the connection. U.S. Pat. No. 3,800,388 shows a connector for use in an optical transmission line wherein the relative positions of the fiber ends can be changed and the optimum relative position of the fiber ends established by monitoring the intensity of light transmitted through the link. However, this does not provide a permanent joint and disadvantageously requires access to at least one end of the link to introduce the test signal for alignment.
For the above reasons a need exists for optical waveguide splicing apparatus in the form of a portable instrument which permits field splicing with opt:cal monitoring to insure optimum core alignment and without any need for peripheral supporting equipment or access to far ends of a cable or waveguide fiber being spliced.
It is therefore one object of the present invention to provide apparatus for splicing optical waveguide fibers, which is portable and self-contained but with optical fiber alignment capability.
It is a further object of the invention to provide a splicing method utilizing optical alignment but not requiring access to fiber or cable sections other than the end portions of the sections to be spliced.
Other objects and advantages of the invention will become apparent from the following description thereof.